The present invention relates, in general, to the field of magnetoresistive (xe2x80x9cMRxe2x80x9d) and giant magnetoresistive (xe2x80x9cGMRxe2x80x9d) recording heads. More particularly, the present invention relates to a process for producing poles in a magnetic recording head utilizing sputtered materials and a magnetic recording head made thereby.
MR and GMR read heads, or sensors, are known to be useful in reading data from a magnetic surface with a sensitivity exceeding that of inductive or other thin-film heads. In operation, the sensor is used to detect magnetic field signal changes encoded on a magnetic surface through a change in resistance which is exhibited due to the direction and strength of the associated magnetic flux being sensed. Currently, the magnetic field signal changes representing the data encoded on the particular storage medium is xe2x80x9creadxe2x80x9d by an MR or GMR read head and xe2x80x9cwrittenxe2x80x9d by a related write, or recording, head. In those instances wherein the read head has associated shield layers, the write head may utilize the xe2x80x9ctopxe2x80x9d shield as a bottom pole thereby providing what is known as a xe2x80x9cmergedxe2x80x9d or xe2x80x9csharedxe2x80x9d shield pole structure. In any event, a typical thin film recording head ultimately comprises two magnetic poles, a top and bottom pole that surround a coil forming a write gap.
In conventional magnetic recording heads, nickel iron (NiFe), or permalloy, is generally used as the pole material. However, as the recording areal density of storage devices continues to increase, more advanced pole materials having a higher magnetic moment are required. While conventional permalloy poles can be produced using well known electroplating techniques and result in relatively well defined edge profiles and good width control, many of the known high magnetic moment materials such as cobalt-zirconium-tantalum (CoZrTa), iron-aluminum-nitride (FeAlN), iron-tantalum-nitride (FeTaN) and iron nitride (FeN) can only be sputter deposited, thereby making it extremely difficult to pattern and produce well defined poles.
Moreover, conventional wet chemical etch processes are also incapable of producing poles with good width control and desirable edge profiles. On the other hand, while dry etch techniques such as ion-milling can provide acceptable width control, they nevertheless result in the re-deposition of the etched materials on the sides of the pole resulting in undesirable xe2x80x9cbunny earxe2x80x9d structures. These structures promote the formation of voids between them following encapsulation (or overcoat), particularly with the narrow pole widths required for higher areal recording density using relatively high magnetic moment materials.
Consequently, there has heretofore been no technique available for producing or achieving well defined poles free of xe2x80x9cbunny earsxe2x80x9d in a magnetic recording head using sputter deposited materials such as currently known high magnetic moment materials.
In accordance with the technique of the present invention, a magnetic recording head and process for producing the same is provided wherein a relatively high magnetic moment material is sputter deposited or otherwise formed on a substrate. A standard photoresist pattern is then applied to the high magnetic moment material layer to define the desired pole. A first wet chemical etch step is then utilized to produce a predetermined amount of lateral etch and a predetermined amount of etch depth beneath the photoresist. In a preferred embodiment, the ratio of the lateral etch to the etch depth is advantageously on the order of 3:1 or greater in order to facilitate the establishment of a substantially discontinuous, or weakly linked, layer of re-deposited material on the sides of the photoresist and high magnetic moment material. A subsequent dry etch step, such as ion milling, is then used to etch the remaining part of the relatively high magnetic moment material layer using timed etch or end point detection.
Because ion milling is a relatively long operation, re-deposition of the etched material occurs and the skin of the photoresist tends to harden making it more difficult for the solvent in a subsequent photoresist removal step to penetrate the photoresist. In this regard, the substantial discontinuity, or weak link, formed in the re-deposited material due to the lateral undercut serves to facilitate the later removal of the photoresist solvent. A pre-treatment oxygen plasma step to further reduce the hardened skin of the photoresist prior to a standard photoresist strip step may also be used.
At this point, an additional technique in accordance with the disclosure herein may be employed wherein a gaseous material, e.g. liquid carbon dioxide (CO2), is employed to further reduce the re-deposited material. In operation, the liquid carbon dioxide may be passed through a nozzle through which it is expanded and a substantially steady flow of fast-moving carbon dioxide particles and carbon dioxide gas is formed. By directing this stream at the resultant recording head structure, the particles serve to remove any re-deposited material, which loosened material is then carried away by the carbon dioxide gas.
Particularly disclosed herein is process for producing a magnetic recording head pole and a recording head made by a process comprising the steps of providing a substrate, forming a layer of relatively high magnetic moment material on a surface of the substrate and patterning a photoresist area on an exposed surface of the formed layer to define the pole. A portion of the exposed surface of the formed layer at least partially underlying the photoresist area is removed to a predetermined lateral width and depth, the formed layer surrounding the photoresist area is further removed to produce the pole, the photoresist area overlying the pole is then stripped away and any re-deposited material remaining on the pole is substantially removed.
Further disclosed herein is a process for removing re-deposited material in a thin film device structure which comprises the steps of providing a source of a gaseous material and directing the gaseous material through a nozzle directed toward the thin film device to produce particles and an associated gas comprising the gaseous material. The re-deposited material is respectively removed and carried away from the device structure by the particles and associated gas.